Method of operating pebble-type heat-carriers



Dec. 4, 1956 F. DANULAT ET Ax. 2,772,873

METHOQ 0F OPERATING PEBBLE-TYPE HEAWCARRIERS Flled Jan. zo, 1952 s sheets-sheet 1 3 Ff@ f .Inventor Dei:- 4, 1956 F. DANuLA-r ETAL E 2,772,873

METHOD 0F' OPERATING PEBBLE-TYPE HEAT-CARRIERS Filed Jan. 30, 1952 3 Sheets-Sheet 2 ffy. Z

IAlvE/vTo/s: Jambcg g2, g we Aww @Je ma Ef' 7a4/9L Dec. 4, 1956 F DANULAT ETAL METHOD oF OPERATING. PEBBLE-TYPE HEAT-CARRIERS Filed Jan. 5o. 1952.

5 Sheets-Sheet 3 5277*@ mvg/5 United States Patent() METHOD OF OPERATING PEBBLE-TYPE HEAT-CARRIERS Application January 30, 1952, serial No. 268,988 Claims priority, application Germany February 2, 1951 s Claims'. (cl, 263-52) This invention relates to improvements in the use of pebble-type heat carriers.` yIt more particularly relates to an improvement in the discharge of pebble-type heat carriers from the thermal process apparatus for recycling.

A huid-type heater is known in which pebble-type ren ractory heat carriers pass consecutively through at least two chambers. The heat carriers are heated b`y combustion gases or the like in the lirst chamber and transfer their heat to fluids which are passed in counter-current iiow contact with them in the lower chamber. The heat carriers are then discharged from the lower chamber and conveyed back up for passage through the top chamber by a conveying device. Y'

A method for effecting thermal processes as the gasification of finely granular or pulverulent fuels is de scribed in U. S. Patent application Serial No'- 172,342, tiled July 6, 1950, now Patent No. 2,701,758. According to said application, pebble-type heat carriers of from granular to lumpy or ball size are heated and suspensions of nely divided material to be thermally-acted upon are caused to iiow through the interspaces between the carriet particles to transmit the heat from the carriers to the suspensions. The heat carriers are then discharged from the thermal process chamber and conveyed by conveying device as, for example, a bucket conveyor or pneumatic conveying system back to be heated and again passed through the thermal process zone. In an embodiment of the method described in the said application the heat carriers are passed downwardly successively through three zones, discharged from the'last zone, conveyed back up for passage again through the iirst Zone. In the first zone the carriers are heated by means of combustion gases or the like. The heated carriers then flow through a constriction to the secondzone in which a suspension of tinely divided fuel to be gasiiied is passed upward through the interspaces between the heat'carrier f in exchange therewith and the gas formed is .removed from the top of this second Zone. After passage through the second'zone, heat carrier passes through a constriction and through a third zone through which steam is circulated in counter-current heat-exchange relation to the heatV carrier. The steam is superheated, and a portion ,of the steam passes up to the second zone and acts as for the discharge of the heat carrier-with themaintainingV pf pressure inthe last zonecauses a, crushing and dis- 2,772,873 Patented Dec. 4, 1956 ICC a integration of the heat carrier which leads to serious operational diculties.

One object of this invention isV the discharging of pebbletype heat carriers in the last reaction zone without the aforementioned disadvantages.

A further object of this invention is the discharging of pebble-type heat carriers from the last thermal process zone in a uniform andcontrolled mannerwithout causing a crushing or disintegration of the heat carriers while maintaining a pressure higher than atmospheric in this last zone. These and still further objectsiwill become apparent ,from the following description read in conjunction with the drawings. i

Fig. l `shows ldiagramatically a vertical section of an embodiment of an apparatus in accordance with theinvention. v

ln Fig. 2 another embodiment of an apparatus in accordance with the invention is shown in the same manner.

Fig. 3 shows the lower part of an apparatus in accordance with the invention in an enlarged scale.

yIn, accordance with the invention the heat carriers are discharged from the thermal process apparatus for recycling through an elongated channel having a nar row cross-section, as, for'example, a pipe section of suitable length. A funnel-shaped path may be established in the lower portion of the apparatus which leads into the narrow channels and the heat carriers will enter the channel through this funnel-like inlet. The channel should be formed with its bottom portion `open and a support should be positioned in spaced relation to the open channel bottom so that the heat carriers will pile up'at the open channel discharge end on the support and discharge from this pile between the channel end and the support. it is preferable that the distance from the channel end and the support be made adjustable.

kFrom the pile of heat carrier formed between theV riers `for recycling back through the thermal process ap-V paratus. `The new discharging of the heat'carrier, in acl cordance with the invention, completely eliminates the i from the lower open discharge end of the channel may,

for"exarnple,'be in the form of a rotating discharge belt. By adjusting the speed `of this belt and its distance fronrthe channel discharge end, the-quantity of the heat carriers discharged may be accurately controlled. lt is possible by suitable adjustment of the speed of the beltV or the distance of the belt from the channel end, to adjust'within wide limits the quantity of `the heat carriers removed, 9 f A i 4 Y Inl order to mainta-infthe'desired gas pressure in the thermal process zone 4or chamber, from which the heat ca-riersfare discharged to thei conveying apparatus, a gaseous vmedium and preferably steam is introduced into the channel and passed downward therethrough; The gaseous medium -is allowed to discharge freely at the end ofthe channel. vAs the Vgaseous medium -iows downward Ithrough the heat carriers, 'a pressure loss occurs, so that a pressure differential is brought about between the upper 'and lower channel ends and a pressure greater than atmospheric, may be maintained in lthe chamber -or'zone from which the fheat carriers are discharged.

Vend thereoffor further use.

In order -to keep the quantity of the downwardly flowing gaseous medium small, the channel should -be constructed as long and -as narrow 'as is possible. On the other hand, the-channel should not be so long and narrow that bridging or clogging of the individual granules of heat carrier occurs or that the velocity of the'heat Icarrier in the channel becomes too high. If, for example, polygonal or spherioally shaped heat carriers having a panticle size of about ten millimeters vin diameter Iare used, `a discharge channel having a diameter, for example, o'f60 to 80 mm. is suitable. The length 'of `the channel is preferably adapted to the Vexcess pressure required in the chamber or zone from which the heat carriers lare discharged, and `to the permissible quanti-ty of |the discharging gaseous medium. In general, channel 'sections having Vlengths of between 1 ,and 4 `meters are suicient even when `the excess pressure in 'the chamber or zone, from which the heat carriers are to be discharged, is as high as one atmosphere in excess of atmospheric pressure. The required speed of gaseous mediums for producing in the channel the necessary `loss in pressure which equals the pressure difference of the last chamber compared Awith the atmosphere,rrstly depends on the condition of the gaseous medium, the size and type of the heat carriers and the diameter of the channel. For example: At a speed of the gaseous medium of about l m./sec. calculated on the cross section of the channel a pressure difference of about 2000 mm water column per meter pipe length lwill .be obtained. Pressure loss increa-ses with the square of the `speed'of the gaseous medium.

The gaseous medium used ifor maintaining the pressure in the chamber or zone, from which the he-at carriers are to Ibe discharged, may be introduced near the place Y in the channel where the heat carriers enter the channel.

As mentioned above, steam may .advantageously be used yas this gaseous medium.Y The gaseous medium such as steam, after passage through the channel, may be blown out through the llower open end of the channel.

If the Zone or chamber from which the heat carriers are to be discharged is already rilled with steam, as, `for example, in fthe embodiment .set -forth in U. S. patent application Serial No. 172,342, in which 'the gasifying steam is formed in the last chamber, and in which the steam is superheated in this chamber, a portion of this ysteam may be introduced Ias Vthe gaseous medium for passage through the channel and maintaining the pressure inthe Zone -or chamber. Y

The discharging steam or other gaseous medium assumes lapproximately the same temperature las Ithe temperature of the heat carrier being Vdischarged which, for example, may be between 100 and `600 C. depending on the nature of the thermal process being eiected. The gas used 'as the sealing agent is conducted out through the discharge lchannel 'and may be collected lat the lower lf steam is used, for example, it may be compressed `aiiter its discharge and used ing of materials such 'as lfuels `used in the thermal process or else for other purposes as, for-the Vgasiica'tion or degasitication of fuels, the preheating of water, etc.

The apparatus shown in Fig. 1 by way of example is [of the type -described in U. S. patentapplication Serial No. 172,342 with a lower chamber Vfrom 'which the heat carrierdischarges and through `which steam is circulated.

The beat carriers pass `from ja bunker, heateror the like 1 throughchannel 2V-into zone y3 in which` the intended thermalV process `takesplacfe, whereupon they pass 'into zone '4,V In zone 4 steam is superhea'ted in heat *exchange with the heat carriers. The steam is forced by blower 5 to recycle through zone 4 and evaporator 6. This evaporator `6, Ithe blower 5 andthe zone 4 are connected with each other by lconduits 7, `8l and 9. By the injection of water which -fiows into evaporator 6 through Ythe line l0, the superheatedstcam is cooled and additional steam its produced. From one 4.. a part of the steam hows.-

into zone 3 through constriction 11, while `another part returns to the evaporator y6 through openings |12 .and line 7. Another portion of the steam flows below inlet y13 and passes downward int-o thel discharge channel formed `as pipe '14.

From the lower end l15 of pipe 14 the heat carriers ow onto a constantly moving discharge belt 16 which depending on its speed removes -a definite quantity of heat carriers. From the discharge belt 16 the heat carriers are introduced, via chute 117, which may be developed as a lscreen'in order to rem-ove the undersize particles, to elevator 18 @which returns the heat carriers, -for example, directly into the chamber v1. The discharge belt may be horizontal, or may, =for example, also `be inclined obliquely downwards or upwards. Y The discharge belt and elevator may, however, also be constructedina single unit and the heat carriers'. returned from pipe'14 directly into receptacle 1 by means of this unit. The Vquantity of heat carriers which is removed from pipe 1'4 per unit of time can be regulated by the speed of the discharge belt, by the -bed height of "the heat carrier on the discharge belt or by both of lthese means combined. For the adjustment of Ythe `bed height there may be used, for instance, a dam again as a sealing agentor used for the drying or preheatlkonwn manner.

or weir 19 of adjustable height arranged at the `discharge endflS of the pipe length. Instead-of the discharging belt 16, yany support mean-s may be positioned -at 4a rtxed distance from the discharge end 15 of the pipe 14. The support should be positioned at such -a distance -from this discharge end 15 that the heat carriers will pile up Von the support below the end 15 and be discharged from this pile.

(charge belt 16. lt is fitted for instance with a spur rack 25 and a gear wheel 26. On shaft 27 of the gear wheel 26 there is a hand wheel 28, whereby shaft 27 is resting on a xed bearing block 29. By operating handwheel 2S the Weir can be moved upward and downward by means of gear wheel 26 and rack 25, whereby bed height 24 changes accordingly.

Pipe 14 is advantageously Eformed with a widened part 20 shortly before its lower end in which the downward flowing lvapor can discharge out of the charge of heat carrier and be led away through line 21. Line 21 can be connected directly to a stack; however it may also lead to an apparatus in which the steam itself or its heat isurtherused. The pressure with which this steam leaves pipe 14 can be varied, independently of the pressure prevailing in zone 4, by arranging the discharge 29 at a higher or lower position on pipe 14. In this connection steam lcan also be permitted to o'w off at the lower end 15 .of kpipe 14 or else a second steamtap can be `provided shortly above the lower end 15 through which Vsteam can be removed.`

The rest of the apparatus-isV operated in the manner described in said patent application Serial No. 172,342 in which uids or suspensions are introduced into the chamber 3 through'the pipe 23 inthe opening 22.

Fig. 2 shows a modification of the apparatus inV which chamber 4 of Fig. lV including its devices for the production and overheating of steam necessary in the process are omitted.` "111e gaseous or vaporous medium necessary`for the thermalV process is being introduced in Vthis case through pipe 30 into Lroom 31 andl passes v cally.

line 33, the steam owing downward in pipe 14, thus causing a pressure reduction corresponding to the excess pressure prevalent in chamber 31 as compared with the atmosphere. 1n order to prevent passage of steam upwards from pipe 33, into room 31 and thence into chamber 3, and in order to likewise prevent part of the gaseous or vaporous medium in room 31 from iiowing downward through pipe 14, advantage is taken of the pressure diiference between the widening 32 and the low part 34 of room 31. This pressure diierence is determined and indicated by known means. Depending on this pressure diierence the vapor introduction'into widening 32 can be advantageously regulated automati- I'n order to indicate by measurement the difference in pressure already in a weak iiowing of a gaseous or vaporous medium yfrom 32 -to 34, the widening 32 is Vbeing fixed in a suficient distance from lower part 34. For instance this distance should suitably amount to the double or fourfold of the diameter of pipe 14.

What we claim is:

1. In a method for effecting thermal processes in which heat carriers are passed downward through at least one thermal process zone having a pressure in excess of atmospheric, the improvement for discharging the heat carriers from the zone while maintaining the operating pressure in said Zone, which comprises establishing a long, narrow, downward discharge path for heat carriers from said Zone, and passing heat carriers out of said zone through said discharge path while, simultaneously therewith, passing gaseous medium under pressure through said discharge path in co-current ow with said heat carriers.

2. Improvement according to claim 1, which includes maintaining a pile of heat carriers at the discharge end of said discharge path and removing the heat carriers from this pile.

3. Improvement according to claim 1, which includes recovering the gaseous medium passed through said discharge path.

4. Improvement according to claim 1, in which said gaseous medium is steam.

5. Improvement according to claim 1 which comprises passing said gaseous medium into said thermal process Zone above said downward discharge path whereby a portion ythereof goes downward in co-current iiow with said heat carrier material and a portion flows upward through said zone counter-current with said carrier material.

References Cited in the file of this patent UNITED STATES PATENTS Royster Sept. 19, 1950 

